There is increasing evidence for the existence of a family of tumor suppressor genes that are involved in different cancers. Using a technique known as microcell-mediated chromosome transfer, the Laboratory of Molecular Carcinogenesis, in collaboration with Dr. Mitsuo Oshimura (Tottori University, Japan), has mapped tumor suppressor genes involved in human and rodent cancers to chromosome 1 (endometrial cancer, fibrosarcomas), chromosome 3 (renal cancer, lung cancer), chromosome 6 (endometrial cancer), chromosome 7 (choriocarcinoma), chromosome 9 (endometrial cancer), and chromosome 11 (cervical cancer, Wilms' tumor, rhabdomyosarcoma, lung cancer, fibrosarcoma). These studies have shown 1) that different members of the family of tumor suppressor genes can be mapped to different chromosomes; 2) that more than one normal chromosome can suppress the tumorigenicity of a given tumor line, which indicates that multiple tumor suppressor genes are Involved in certain tumors (e.g., chromosomes 1, 6, and 9 i endometrial cancer and chromosomes 3 and 11 in lung adenocarcinoma); 3) that gen dosage effects can be observed (i.e., one copy of a suppressing chromosome can suppress certain tumors; other tumors require two copies); and 4) that functionally distinct tumor suppressor genes can be identified (suppression of tumorigenicity can occur with or without cellular senescence or growth suppression).